ANTILOCKING BRAKE SYSTEM

K. Bharath Kanna B.E MechProject Associate, NITTTR Chennai.

Introduction

Antilock braking systems (ABS) are electronic systems that monitor and control wheel slip during vehicle braking.

ABS can improve vehicle control during braking, and reduce stopping distances on slippery road surfaces by limiting wheel slip and minimizing lockup.

Reducing wheel slip improves vehicle stability and control during braking, since stability increases as wheel slip decreases.

Comparison

Simple hydraulic braking system

A simple braking system consists of a master cylinder, and four wheel cylinders.

When the brake pedal is pressed the piston in the master cylinder forces the liquid out of the cylinder. This liquid presses the two pistons in the wheel cylinders outwards. These two pistons push the brake shoes outwards.

Working When the pedal is pressed

the primary piston moves to the left .

when it crosses the bypass port the liquid is forced along the pipe lines to the wheel cylinders.

When the pedal is released the primary piston is moved back wards .it is the spring, which pushes the piston back wards

Principles of ABS The skidding and loss

of control was caused by the locking of wheels.

The release and reapply of the brake pedal will avoid the locking of the wheels which in turn avoid the skidding.

This is exactly what an antilock braking system does.

Pressure Modulation

When the brake pedal is pumped or pulsed the pressure is quickly applied and released at the wheels. This is called “pressure modulation”. Pressure modulation works to prevent the wheel locking.

ABS can modulate the pressure to the brake as often as 15 times per seconds.

ABS Components

Speed Sensor. Gear pulser. Hydraulic Control

Unit. ( Pump, Solenoid Valves, Master Cylinder).

Electronic Control Unit (or) Control Module.

Features and Benefits

o Control of steering

o Fail-safe electronic system.

o Traction control o ABS Malfunction Indicator Lamp

o Increases steering ability and vehicle stability during braking.o If the electrical/electronic system fails, the ABS is shut off.o It controls excessive wheel spin during acceleration.o Informs the driver or technician that an ABS fault has occurred.

Disadvantages

It is very costly.

Maintenance cost of a car equipped with ABS is more.

Conclusion

Statistics show that approximately 40 % of automobile accidents are due to skidding.

These problems commonly occur on vehicle with conventional brake system which can be avoided by adding devices called ABS.

If there is an ABS failure, the system will revert to normal brake operation. Normally the ABS warning light will turn on and let the driver know there is a fault.

Thank You